1. Field of the Invention
The field of the present invention relates generally to devices and methods which prevent, inhibit or impede the build-up of bacteria in water lines which connect dental or medical tools to a source of water. More particularly, the present invention relates to sterilizable water lines and pre-filters that connect dental handset tools (air/water syringe dental handpiece, or ultrasonic scaling device) to a supply of water to prevent bacteria from passing through the tool to the patient.
2. Background
In recent years, much media concern and in some cases criticism has been focused on the equipment and processes utilized by dental personnel regarding the transmission of microorganisms during dental procedures. Much of this attention has been focused on unsterilized fluids being introduced into a patient's mouth and exposed tissues. These microorganisms may result in harmful illnesses that are difficult to treat. As more progress and knowledge is gained regarding this problem, modern dental practices attempt to reduce the potential for transmission of microorganisms. However, the very nature of many dental procedures, which continue to be somewhat invasive, and the current state of technology makes this task difficult to completely resolve.
One source of potential concern is the water that is injected into the patient's mouth during a number of different dental and oral surgical procedures. For instance, water is used to rinse off scale and tartar debris that is released from ultrasonic scaling and cleaning procedures. The injection of water allows the dental personnel to better determine which areas need cleaning and allows the patient to remove the debris from the mouth. The use of high-speed dental tools for drilling and grinding, which can generate significant heat, are made somewhat less painful by the injection of a small stream of water to cool the tools. Water is also used to remove debris from the drilling. Other specialized equipment also requires the injection of water and air/water spray into the patien's mouth. When used with dental water syringes, the water is commonly supplied into the patien's mouth at a pressure of about .+-.40 psi.
The source of water for most dental offices is city tap water that is conveyed through a dental unit workstation to thermoplastic tubing connected to the dental tools. Often these workstations do not employ filtering systems to filter bacteria and other contaminants from the water source, as there is no legal standard to require this at present. Despite this, recent national media attention and criticism has focused on the problems with city water that is injected into the patien's mouth. According to published reports, the city water or other water entering the dental tools is often contaminated with significant levels of various microorganisms. Also, water left in the water lines incubates and forms a biofilm which increases the bio-burden that is injected into patients' mouth. Because many dental procedures are invasive and result in some bleeding in the patien's mouth, it is possible for this bacteria to enter the person's blood stream and, possibly, result in illness for the patient. This is a particular concern for those patients with weakened immune systems, the very young, the elderly and those who are already ill.
Much progress has occurred relative to the sterilization of dental tools to prevent the tools, themselves, from being a source of contaminate transmission. In recent years, OSHA and others have set guidelines that require dental tools to be sterilized on a routine basis. The typical sterilization procedure used in dental offices is to place the dental tools to be sterilized in an autoclave for approximately 30 minutes. The autoclave is a self-contained unit that heats the dental tools to an elevated temperature of approximately 132 degrees C. (270 degrees F.) at a pressure of approximately 15 psi. This procedure has been found to be very effective for eliminating the patient to patient cross contamination and transmission of bacteria by the dental tools, which are typically manufactured out of stainless steel and similar autoclaveable materials. However, the high temperatures in the autoclave are known to deteriorate the materials used for existing water lines and, consequently, the autoclave has not been used to sterilize water lines due to their fragility. Also, water lines heretofore have not been detachable for the purpose of sterilization.
Research by others have indicated that the small bore water lines utilized in the dental profession have a tendency to accumulate a layer of biofilm, consisting of a form a mucopolysaccharide slime and microorganisms, on the inside of the water line. This biofilm is formed when water sits in the water line at room temperature for hours without circulation, allowing bacteria in the lines to multiply in the biofilm and adhere to the walls of the water line. Once established, the biofilm cannot easily be removed by conventional cleaning. The bacteria in the biofilm are shed from the biofilm into the water that is injected into the patien's mouth. While most dental tools and equipment can be effectively sterilized by the use of autoclave systems, the biofilm in the water lines is upstream of the dental tool and not included in such cleaning of the dental tools. Also the water lines are susceptible to deterioration by heat and therefore not autoclaved. Prior art dental water lines have one or more small bores, and they are typically molded from a thermoplastic or plastic-composite material. The high temperature inside the autoclave can damage or even melt these prior art water lines, making the autoclave ineffective for sterilization. Because the biofilm attaches itself to the inside of the line and tends to become entrenched in the line, it is difficult to remove by other sterilization procedures (i.e., chemical processes). In addition to being difficult to remove, if the biofilm is removed by a particular cleaning process, it tends to quickly and easily re-establish itself in the water line, thereby requiring frequent re-cleaning of the water line.
Several previous inventions have attempted to address the problem of biofilm accumulation in water lines. For instance, U.S. Pat. No. 5,204,004 to Johnson, et al. and U.S. Pat. No. 5,554,025 to Kinsel have both addressed the problem of biofilm accumulation in dental water lines. Both Johnson and Kinsel disclose filters that are intended to filter out contaminants after the line but before they are injected into the patien's mouth (i.e. at the dental handpiece). Johnson places a post water line filter on the water line a small distance before the dental syringe. Kinsel utilizes a filter located between the syringe tip and the dental handset outlet fitting. Choosing to rely on filters, neither Johnson or Kinsel address the accumulation or removal of biofilm in the water line between the filter and the dental tool. However short that this line may be, it still continues to grow biofilm. Therefore, what is needed is a method and/or detachable device to prevent, control or reduce the accumulation of biofilm in the water line and to reduce its bio-activity by use of commonly available sterilization methods, such as autoclaving.